There has been known that in a rolling device such as a rolling bearing used under high load or vibratory load environment, a lubricant film intervening between a raceway surface and a rolling element is broken during use and lubricating performance declines drastically, thereby causing damage such as wear or seizure on the raceway surface and the surface of the rolling element.
In order to improve seizure resistance of a grease composition, generally, there has been carried out that a grease composition comprising a high viscosity base oil having a kinematic viscosity of 100 m2/s or more at 40° C. and an extreme pressure agent is used or a used amount of the grease composition is increased. However, while these solutions improve seizure resistance, there is a problem that resistance to stirring in the rolling device is increased.
Also, Patent Document 1 discloses grease prepared using, as a thickener, a diurea compound obtained by allowing an amine mixture comprising alkylphenylamine, an alkyl group of which has 8 to 16 carbon atoms, and cyclohexylamine in a molar ratio of 1:9 to 9:1, to react with a diisocyanate compound. However, it is not considered that a worked penetration is adjusted to 300 to 330.